The use of contact lenses for correcting focal length-related vision impairments such as myopia, hyperopia, and presbyopia is well known. Non-surgical techniques for correcting myopia (short-sightedness) and hyperopia (far-sightedness) typically include glasses or contact lenses. Presbyopia is most commonly corrected with reading glasses. However, a given individual can have two of the above vision impairments, for example, both myopia and presbyopia. In such a case, the individual is often forced to switch between multiple pairs of glasses, wear bifocals, or wear contact lenses to correct for the myopia and reading glasses to correct for the presbyopia. Alternatively, the individual can be given a contact lens for one eye that corrects the myopia and a contact lens for the other eye that corrects the presbyopia.
Active contact lens systems that adjust in the eye to correct different vision requirements are an emerging area of ophthalmology. Blum et al in U.S. Pat. No. 6,851,805 entitled “Stabilized electro-active contact lens,” issued Feb. 8, 2005 teaches an electro-active contact lens system and a method for making the electro-active contact lens system. The system includes a contact lens, an electro-active element attached to the contact lens, a view detector attached to the contact lens and in electronic communication with the electro-active element, and a power source attached to the contact lens. In certain embodiments, the view detector can be a rangefinder which determines the distance of an object being viewed. These embodiments further include a means to stabilize the rangefinder between the opening of the eyelids when the electro-active contact lens system is worn by a wearer. The electro-active contact lens system provides electro-active vision correction of one or more focal lengths.